Filaments and Cathodes

Overview


Overview

Rave Scientific offers a wide variety of electron microscope emitters. Our Tungsten, Lab6 and Schottky emitters are compatible with all major brands of scanning and transmission electron microscopes, including all FIB-SEM workstations. Our emitters are of high quality and are manufactured to exceed the specifications of the original equipment manufacturers. The following Electron Source Performance Table is provided to give you additional information regarding the performance and requirements for different types of electron emitters. Tungsten cathodes are still used in the majority of all SEMs and in general use TEMs. Improved results can be obtained with LaB6 cathodes, whereas the highest resolution can be obtained with either Schottky or cold Field Emission Sources which can only be used in suitable EMs.

Emitter TypeThermionicThermionicSchottky FECold FE
Cathode Material W LaB6 ZrO/W (100) W (310)
Operating Temp (K) 2700 1800 1800 300
Cathode Radius (nm) 60,000 10,000 <1000 <100
Effective Source Radius (µm) 25 10 0.015 0.0025
Emission Current Density (A/cm2) 3 30 5300 17,000
Total Emission Current (µA) 200 80 200 5
Brightness (A/cm2.sr.kV) 1x104 1x105 1x107 2x107
Maximum Probe Current (nA) 1000 1000 10 0.2
Energy Spread @ Cathode (ev) 0.59 0.4 0.31 0.26
Energy Spread @ Source Exit (eV) 1.5 – 2.5 1.3 – 2.5 0.35 – 0.7 0.3 – 0.7
Beam Noise (%) 1 1 1 5 – 10
Emission Current Drift (%/h) 0.1 0.2 <0.5 5
Operating Vacuum (hPa/mbar) <10-5 <10-6 <10-8 <10-10
Typical Cathode Life (h) 100 >1000 >5000 >2000
Cathode Regeneration (h) None None None 6-12
Sensitivity to External Influences Minimal Low Low High